The present invention relates to numerical control devices (NC devices) provided in numerical control machine (NC machine tools), and more particularly, to NC devices capable of generating audio instructions.
Conventionally, NC devices that inform the operator of problems occurring in NC machine tools through voice generation or by means of displays have been known. Also, an NC device described in Japanese Laid-Open Patent Publication No. 5-19829 computes, for example, an estimated time for performing a periodic inspection and announces this time to the operator using a generated voice, thus improving work efficiency.
More specifically, for example, an estimated operation time consumed by executing a machining instruction program is preset in the NC device. The NC device computes an estimated operation end time in accordance with the preset value and announces the obtained time by means of a voice generator.
However, the NC machine tool of the aforementioned document generates the voice for announcing the estimated operation end time or a problem occurring in the machine tool, regardless of whether or not the operator is located in an audible range of the voice. That is, the voice is generated unnecessarily if the announcement is inaudible to the operator. In this case, the information is not reliably provided to the operator.